Conventionally, there has been known a heat treatment apparatus having a gas pipe connecting structure for connecting a plurality of gas pipes to a predetermined gas introduction part of a processing container in order to introduce a plurality of kinds of gases into the processing container.
For example, in the conventional heat treatment apparatus, a gas introduction passage is formed in a sidewall of the processing container, and a horizontal portion of an L-shaped injector made of quartz is inserted into a portion of the gas introduction passage on the side of the processing container. Further, connection structures that can establish a connection by means of a thread-engaging mechanism similar to a bolt and a nut are provided at an outer peripheral surface of a flange and a leading end of a gas pipe, and an O-ring is also provided at an outside of the gas introduction passage, so that when the gas pipe is connected to the flange by the aforementioned thread-engaging mechanism, the gas can be hermetically introduced from the gas pipe into the processing container.
In the gas pipe connection structure described above, since it was necessary to install the O-ring and the thread-engaging mechanism similar to the bolt and the nut, some extent of space was required at a place where the gas pipe is connected. Moreover, since the horizontal portion of the L-shaped injector made of quartz was inserted into and fixed to the gas introduction passage, it was necessary to thicken the horizontal portion of the injector in order to secure a predetermined strength. As such, in the gas pipe connection structure, from the viewpoint of the connection structure employing the thread-engaging mechanism and the securement of the strength of the injector, it was difficult to reduce a pitch between injectors so that there was a limitation on the number of the injectors to be installed, for example, an upper limit of the number of the injectors was about nine.
Meanwhile, in a film deposition process using a recent vertical type heat treatment apparatus, it is required to uniformly perform the film deposition processing over a plurality of substrates stacked in a vertical direction, in an up and down direction of the substrates, and thus, there is a need for an apparatus enabling a process of individually supply a gas to each of areas arranged in the vertical direction. In this process, there is a need for installation of an injector for each of the areas and a plurality of injectors needs to be used in a process for one lot of substrates.